DENTAL AGE IN KELANTANESE MALAY POPULATION

BASED ON DEMIRJIAN'S METHOD

By

Dr. SAIFEDDIN HAlVIED ABU ASAB

The.sis Submitted In Fulfillment Of the Requirements

For The Degree of Master of Science in Dentistry

(Paedodontic)

Jan 2009

DEDICATION

To

My beloved family

..

11

ACKNOWLEDGEMENT

First of all, I thank Allah (S.W) for giving me the strength and courage to preserve

throughout the duration of this research project and made all of this and everything

possible.

I am deeply grateful to Dr. Siti Noor Fazliah Mohd Noor for continued encouragement,

unceasing efforts, for her persistent motivation. support, great knowledge of clinical

work and leadership throughout my research project. Thanks a lot Dr. Siti Noor Fazliah

for reading my numerous revisions with much patience and tolerance.

I'm indebted to my co-supervisor Dr. Mohd Fadhli Khamis for never-ending

encouragement, for inspiration continually received, and continual support and advice

throughout my study.

I would like to extend my thanks to Dr. Mohd Ayub Sadiq for his expert analytical and

mathematical contributions to this project.

I also extend my grateful appreciation and thanks to all my colleagues in the School

Dental Science USM for their friendship and continuous support all the two years.

My sincere thanks go to my brother and friend Dr. Ghalib W. for a decade of a sincere

brotherhood and friendship, for his standing beside me not only in the postgraduate time

111

but also in the undergraduate time, and for his continuous support. Also I would like to

extend my grateful appreciations to his family for their encouragement all the period of

my study.

Special thanks to Mr. Hakim, Mrs. Suhaila. and Ms. Haizan for their kind assistance

throughout my study.

My respect and appreciation to all the staff in the Radiology department in HUSM and

the staff in Peadodontic and Orthodontic clinics in HKB for their kind help and support

throughout my study.

Special thank to USM for funding this research through grant No: 304/PPSG/613155.

To all named and unnamed helpers and friends, I again extend my thanks.

Dr. Saifeddin Hamed Abu Asab

iv

TABLES OF CONTENTS

Acknowledgment Tables of contents List of Tables List of Figures List of Abbreviations Abstrak Abstract

CHAPTER 1 -INTRODUCTION

1.1 Introduction 1.2 The justification of the study 1.3 General objective 1.4 Specific objectives 1.5 Hypothesis

CHAPTER 2 - LITERATURE REVIEW

2.1 Tooth formation 2.1.1 Dentinogenesis 2.1.2 Amelogenesis 2.1.3 Crown formation 2.1.4 Development of the tooth root

2.2 Age estimation at death for sub-adults 2.2.1 Skeletal tissues methods for sub-adults

2.2.1.1 Union of primary ossification centers 2.2.1.2 Epiphysial union 2.2.1.3 Long bones lengths

2.2.2 Dental tissues methods for sub-adult 2.2.2.1 Eruption time and teeth counts 2.2.2.3 Radiographic methods

2.2.2.3.1 Demirjian's Method (1973)

2.2.2.3.2 Demirjian's method (1976) 2.3 Factors affecting dental development

2.3.1 Genetic factors 2.3.2 Environmental factors

2.3.2.1 Socioeconomic status 2.3.2.2 Secular trends 2.3.2.3 Low birth weight

v

lll

v X

Xl

Xll

Xlll

XVll

1 3 4 4 4

5 7 7 8 9 10 11 12 14 17 17 18 20

23

30 37 38 42 42 44 45

3.8 Statistical analysis 3. 9 Reproducibility of the measurements 3.10 Ethical approval

CHAPTER 4- RESULTS

4.1 Background of the samples 4.2 Reproducibility of the measurements 4.3 Accuracy of Demirjian's methods (1973, and 1976) on Kelantanese

Malay children 4.3.1 The accuracy ofDemirjian's method (1973) 4.3.2 The accuracy ofDemirjian's method (1976) (4 teeth: M2.

4.3.3

Ml, PM2, PMl)

The accuracy ofDemirjian's method (1976) (4 teeth: M2, PM2, PM1, Il)

78 81 81

82 83

85

85

86

87

4.4 New dental age standards for Kelantanese Malay population based on 88 Demirjian's method ( 1973)

-t5 The Dental age standards in Kelantanese Malay and French-Canadian 92 populations

4.6 The determination of sexual dimorphism among male and Kelantanese 94

Malay children 4.7 Assessment of the dental age differences between the right and left sides 97 4.8 Median age of attainment for each developmental stage 98

CHAPTER 5- DISCUSSION AND LIMITATIONS

5.1

5.2

Discussion Reproducibility of the measurements

.. 100

101

5.r , The accuracy of Demirjian's methods (1973, and 1976) on Kelantanese 102 Malay children

5.4 The new dental age standards for Kelantanese Malay population 1 04 5.5 The comparison of the dental age standards in Kelantanese Malay and 106

French-Canadian populations

5.6 The determination of sexual dimorphism among male and female 108 Kelantanese Malay children

5. 7 Assessment of the dental age differences between the right and left sides 1 09

Vll

5.8

5.9

Median age of attainment for each development stage

Limitations

CHAPTER 6- CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions 6.2 Recommendations

REFERENCES

APPENDIX

Vlll

110

115

116 117

118

127

LIST OF TABLES

Table 3.1 Self weighted scores for dental stages (7 teeth) - Boys 71 (from Demirjian and Goldstein, 1976)

Table 3.2 Self weighted scores for dental stages (7 teeth) - Girls 71 (from Demirjian and Goldstein, 1976)

Table 3.3 Self-weighted scores 4 teeth: M2, Ml, PM2, PM1 method 75 for Boy's mandibular left side (Demirjian and Goldstein, 1976)

Table 3.4 Self-weighted scores 4 teeth: M2, M1, PM2, PMl method 75 for girls' mandibular left side (Demirjian and Goldstein, 1976)

Table 3.5 Self-weighted scores 4 teeth: M2, PM2, PM I, II method 75 for boys' mandibular left side (Demirjian and Goldstein, 1976)

Table 3.6 Self-weighted scores 4 teeth: M2, PM2, PM1, 11 method 75 for girls' mandibular left side (Demirjian and Goldstein, 1976)

Table 4.1 Distribution of samples according to age and sex 83

Table 4.2 Cohen's kappa values for intra-examiner reliability 84

Table 4.3 Cohen's kappa values for inter-examiner reliability 84

Table 4.4 The kappa value and the interpretations (Altman, 1999) 84

Table 4.5 Difference between chronological age and dental age 85 (years) for all subjects (7 teeth method)

Table 4.6 Difference between chronological age and dental age 86 (years) for all samples (4 teeth: M2, M1, PM2, PM1)

Table 4.7 Difference between chronological age and dental age 87 (years) for all samples(4 teeth: M2, M1, PM2, 11)

Table 4.8 Distribution of the external samples 91 Table 4.9 Difference between chronological age and dental age 91

(years) for all samples

Table 4.10 Difference between chronological age and dental age 93

IX

(years) for boys

Table 4.11 Difference between chronological age and dental age 93 (years) for girls

Table 4.12 Comparison between both sexes in marurity scores for the 9-l 6 years-old-group

Table 4.13 Comparison between both sexes in marurity scores for the 94 7 years-old-group

Table 4.14 Comparison between both sexes in maturity scores for the 95 8 years-old-group

Table 4.15 Comparison between both sexes in marurity scores for the 95 9 years-old-group

Table 4.16 Comparison between both sexes in maturity scores for the 97 10 years-old-group

Table 4.17 Difference in maturity scores and dental age between left 97 and right sides

Table 4.18 Median age of attainment of each stage of each tooth for 98 boys

Table 4.19 Median age of attainment of each stage of each tooth for 98 girls

Table 4.20 Difference in mean ages of attainment for both sexes of 99 each stage for each tooth (girls - boys mean ages)

X

l

LIST OF FIGURES

Figure 2.1 Stages of tooth formation (Bud. Cap. and Bell stages) 7

Figure 2.2 Schematic drawing of Epiphyse, Metaphyse, and Diaphyse 12

Figure 2.3 Schedule of epiphysial union (adapted from Byers (2000)) 16

Figure 2.4 Stages of epiphysial union of the distal femur: a) no union 17 (missing epiphysis); b) unfused; c) fused; d) obliterated

Figure 2.5 The development stages of permanent dentition .,-_, Figure 2.6 An example of open apices measurement 37

Figure 3.1 Kubang Kerian city in Kelantan state 61

Figure 3.2 Flow chart of the study 65

Figure 3.3 Dental maturity percentile- 7 teeth 71

Figure 3.4 Example of Demirjian's method 73

Figure 3.5 Dental maturity percentiles 4 teeth: M2, M1, PM2, PMl 76

Figure 3.6 Dental maturity percentiles 4 teeth: M2, PM2, PMl, I, 77

Figure 4.1 Graph showing the maturity scores and chronologie age for 89 Kelantanese Malay boys

... Figure 4.2 Graph showing the maturity scores and chrmtblogic age for 90

Kelantanese Malay girls

Figure' 4.6 Comparison between maturity score and chronologie age for 96 Kelantanese Malay both sexes

xi

CA DA MS OPG Mz M. PM2 PM1

c h I. SPSS HUSM HKB

LIST OF ABBREVIATIONS

Chronological age Dental age Maturity score Orthopantomogram or Panoramic radiographs Second mandibular permanent molar First mandibular permanent molar Second mandibular permanent premolar First mandibular permanent premolar Permanent mandibular Canine Permanent mandibular lateral incisor Permanent mandibular central incisor Statistical Package for the Social Sciences Hospital Universiti Sains Malaysia Hospital Kota Bharu

xu

ABSTRAK

Umur gigi amat penting untuk menganggarkan umur seseorang individu yang belum

dewasa, membantu pakar pergigian pediatrik dan pakar ortodontik merancang pelan

rawatan yang betul dan membuat penilaian perkembangan tahap gigi untuk sesuatu

masalah perubatan. Demirjian et al. (1973) telah memperkenalkan kaedah radiografi

umur gigi iaitu peringkat kalsifikasi tujuh gigi kekal rahang bawah telah dinilai. Kaedah

ini kemudiannya telah diubah sedikit pada tahun 1976 dan dua kaedah lagi telah di

cadangkan iaitu empat batang gigi telah digunakan sebagai ganti tujuh batang gigi

(Demirjian dan Goldstein, 1976). Kaedah Demirjian masih lagi digunakan secara meluas

dan telah digunakan dalam pelbagai kajian mengenai radiografi umur gigi. Tujuan kajian

mt ialah : 1) untuk memeriksa ketepaten kaedah Demirjian (1973, 1976) dalam

menganggarkan umur kronologi kanak-kanak Melayu di Kelantan, lelaki dan perempuan

yang berumur 5 hingga 16 tahun, 2) untuk mewujudkan standard baru umur gigi untuk

populasi Melayu di Kelantan; jika kaedah Demirjian tidak sesuai untuk digunakan ke

atas populasi Melayu di Kelantan, 3) untuk membandingkan kelok umur gigi di antara

kanak-kanak Melayu di Kelantan dengan kanak-kanak Perancis-Kanada, 4) untuk

menentukan dwimorfisme seksual pada penilaian umur gigi kanak-kartak Melayu di -,

Kelantall 5) untuk mengesan perbezaen umur gigi dan skor kematengan di antara gigi

kakal bahagian bawah kiri dan kanan dan 6) untuk mengesan median umur pencapaian

pada setiap peringkat perkembangan, mengikut peringkat Demirjian untuk tujuh batang

gigi bahagian bawah kiri. Sejumlah 905 radiograf panoramik (OPG) untuk kanak-kanak

Melayu di Kelantan yang berumur 5 hingga 16 tahun telah dikumpul dari unit radiografi

xiii

L ..

di Hospital Universiti Sains Malaysia (HUSM) dan klinik pakar ortodontik di Hospital

Raja. Perempuan Zainab II (HRPZ II). Umur gigi telah dinilai secara keratan lintang

dengan menggunakan kaedah Demirjian ( 1973 dan 1976). Kanak-kanak yang

mempunyai sebarang penyakjt yang diketahui telah menjejaskan perkembangan gigi,

atau mempunyai agenesis di bahagian lengkung bawah telah diketepikan, begitu juga

dengan imej-imej OPG yang bekualiti rendah. Kebolehpercayaan pemeriksa intra dan

inter menunjukkan nilai yang tinggi untuk skor kematangan dan umur gigi. Diskrepensi

pada peringkat gigi adalah tidak lebih atau kurang dari satu peringkat. Nilai kappa untuk

persetujuan antara para pemeriksa adalah dalam korelasi yang baik. Keputusan kajian

menunjukkan bahawa kaedah Demirjian (1973) telah menganggar lebih umur kronologi

sebanyak dengan 1.24 tahun bagi kanak-kanak lelaki dan 1.27 tahun untuk kanak-kanak

perempuan. 4 gigi kaedah: M1, M~, PM2, PM1 telah menganggar lebih umur dengan 1.23

tahun untuk kanak-kanak lelaki dan 1.20 tahun untuk kanak-kanak perempuan.

Manakala 4 gigi kaedah: M2, PM2, PM,, 11 telah menganggar lebih umur dengan 0.64

tahun untuk kanak-kanak lelaki dan 0.71 tahun untuk kanak-kanak perempuan. Oleh

sebab kaedah Demirjian (1973) adalah tidak tepat digunakan kepada kanak-kanak

Melayu di Kelantan, standard umur gigi janita spesifik yang baru dinbahsuai telah

dihasilkan dengan mengubahsuai kaedah Demirjian (1973). Empat puluh tujuh sampel

dari luar yang terdiri dari kanak-kanak Melayu di Kelantan (23 lelaki dan 24 perempuan)

telah di pilih secara rawak dari Hospital Universiti Sains Malaysia (HUSM) bertujuan

utuk menguji ketepatan kaedah Demirjian yang telah diubahsuai untuk populasi Melayu

di Kelantan dan keputusan menunjukkan bahawa perbezaan min di antara umur

kronologi dan umur gigi hanyalah 2 minggu untuk kedua-dua jantina. Untuk

perbandingan perkembangan gigi antara kanak-kanak Melayu di Kelantan dengan

XlV

kanak-kanak. Perancis-Kanada, keputusan menunjukkan bahawa umur gigi kanak.-kanak

lelaki yang lebih muda (7.0-9.99 tahun) adalah tidak berbeza secara statistik daripada

kanak-kanak Perancis-Kanada (P > 0.05). Walau bagaimanapun Selepas umur 10 tahun,

secara statistik, perbezaan menjadi signifikan untuk kanak-kanak lelaki (P < 0.001).

manakala kanak-kanak perempuan lelaki maju pada umur gigi berbanding kanak-kanak

perempuan kanada, pada semua kumpulan umur dan perbezaan adalah signifikan secara

statistik (P <0.05) Kedua-dua kanak-kanak lelaki dan perempuan matang pada umur

yang sama iaitu 6 tahun dan tiada perbezaan yang signifikan secara statistic anatara

kedua duanye. Selepas umur 6 tahun, kanak-kanak perempuan adalah lebiah maju pada

umur gigi berbanding kanak-kanak lelaki untuk semua kumpulan umur (7.00- 10.99

tahun) tiada perbezaan yang signifikan yang didepati pada perkembangan gigi bahagian

bawah kiri jika dibandingkan dengan bahagian gigi bawah kenen (P > 0.05). Median

pencapaian umur untuk setiap peringkat perkembangan, mengikut peringkat Demirjian

untuk 7 gigi kekal bahagian kiri bawah untuk kedua-dua janita, telah dihasilkan dan

keputusan menunjukkan bahawa kanak-kanak perempuan adalah lebih maju pada umur

gigi jika dibandingkan dengan kanak-kanak lelaki, untuk semua gigi kecuali molar yang

pertama. Kesimpulannya, kaedah Demirjian (1973, 1976) menunjukkan bahawa ia tidak .. tepat untuk digunakan, ketika menganggar umur kronologi pada sampel kanak-kanak

Melayu di Kelantan. Pengubahsuaian pada sistem ini menghasilkan satu sistem umur

gigi barn yang mempunyai ketepatan yang lebih baik untuk kanak-kanak Melayu di

Kelantan. Umur gigi kanak-kanak lelaki dan perempuan Melayu di Kelantan adalah

lebih maju berbanding kanak-kanak Perancis-Kanada pada kesemua kumpulan umur

untuk kanak-kanak perempuan dan kumpulan kanak-kanak lelaki yang lebih tua (10

hingga 15.99 tahun). Umur gigi kanak-kanak perempuan di Kelantan adalah lebih maju

XV

jika dibandingkan dengan kanak-kanak lelaki pada semua kumpulan umur dan setiap

peringkat perkembangan gigi. Perkembangan gigi adalah sdaras pada kedua-dua bdah

rahang bawah.

XVI

ABSTRACT

Dental age has a great importance in age estimation for non-adult individuals,

helping the paediatric dentists and orthodontists to produce proper treatment plan,

and assessment of the dental developmental level of certain medical conditions.

Demirjian et a/. ( 1973) introduced a method of radiographic dental age in which the

calcification stages of the seven permanent mandibular teeth were assessed. The

method was revised in 1976 and two methods based four permanent teeth instead of

seven teeth were proposed (Demirjian and Goldstein, 1976). Demirjian's method is

still widely accepted and used in studies of radiographic dental age in different

geographic regions. The purposes of this study were 1) to examine the applicability

of Demirjian's methods (1973, and 1976) for estimating the chronological age of

male and female Kelantanese Malay children aged 5 to 16 years old, 2) to establish a

new dental age standard; if Demirjian's methods were not applicable on the

Kelantanese Malay population, 3) to compare the dental age curves between Malay

children and French-Canadian children, 4) to determine the sexual dimorphism in the

dental.,.qge assessment of Kelantanese Malay children, 5) to detect the differences in

'dental ages' and 'maturity scores' between the lower left permanent teeth and the

1ower right and 6) to detect the median ages of attainment of each stage of dental

development according to Demirjian stages for the lower left seven teeth. A total

number of 905 panoramic radiographs (OPG) of Kelantanese Malay children aged 5

to 16 years old have been collected from radiographic unit in the Universiti Sains

Malaysia (HUSM), and Orthodontic Dental Specialist Clinic - Hospital Raja.

xvii

Perempuan Zainab II (HRPZ II). The dental age has been assessed cross-sectionally

by using Demirjian's methods (1973, and 1976). Children who had any disease that

was known to affect the dental development. or have agenesis in the lower arch were

excluded, as well as, those poor quality OPG images. The intra and inter-examiner

reliability showed high values for 'maturity scores· and 'dental ages·. Discrepancies

in staging the teeth did not exceed one stage more or less. The kappa values for the

agreement between the examiners were in good correlation. The results showed that

Demirjian's method (1973) overestimated the chronological age by 1.24 year for

boys and 1.27 years for girls, respectively. The 4 teeth: M2, M., PM2, PMt method

overestimated the age by 1.23 years for boys and 1.20 years for girls, respectively.

While 4 teeth: M2, PM2, PMt. I1 method overestimated the age by 0.64 year for boys

and 0.71 years for girls, respectively. As Demirjian's method (1973) was not

accurate on Kelantanese Malay children, new modified sex-specific dental age

standards for Kelantanese Malay were produced by modifying Demirjian's method

(1973). An external sample of 47 Kelantanese Malay children (23 boys and 24 girls)

was randomly selected from the Universiti Sains Malaysia Hospital (HUSM) in

order to test the accuracy of the modified Demirjian's method on Kelantanese Malay .. population and results showed that the mean difference between the chronological

-age and dental age is about 2 weeks for both sexes. In comparison between the

dental development between Kelantanese Malay and French-Canadian children,

results showed that the 'dental age' for younger age groups of boys (7.0- 9.99 years)

was not statistically different from French-Canadian children (P > 0.05). However,

after the age 10 years, the difference became statistically significant in boys (P <

0.001 ). On the other hand, girls were more advanced in dental age as compared to

XVlll

r ~·· Canadian girls in all age groups as the difference was statistically significant (P < ;:

0.05). Both boys and girls have similar maturation at 6 years old with no statistically

significant difference between them. After the age group 6 years, the girls were more

advanced in dental age as compared to boys for all age groups (7.00- 10.99 years).

No significant difference was found in the dental development of the lower left teeth

when compared with the right lower teeth (P > 0.05). The median ages of attainment

of each developmental stage according to Dernirjians' stages for the lower

permanent left seven teeth for both sexes have been produced and showed that girls

are more advancement in dental age as compared to boys in all teeth except the first

molar. In conclusion, Demirjians' methods (1973, 1976) showed to be not accurate

to estimate the chronological age in Kelantanese Malay children samples. The

modification of the system had resulted in a new dental age system that is more

precise and more accurate for the Kelantanese Malay children. Dental age is more

advanced in Kelantanese Malay boys and girls as compared to French-Canadian

children in all age groups for girls and older age groups for boys (10 to 15.99 years).

Dental age is more advanced in Kelantanese Malay girls as compared to boys in all

age groups and in all stages of dental development. Dental developmen!_ is m

harmony in both sides of the lower jaw.

XIX

Chapter 1

Introduction

1.1 Introduction

Dental age can be defined as a measure of how far the teeth have progressed towards

maturity (Koch et al .• 1994), or a measure of childhood dental development (Corsini,

1999), and it corresponds to odontogenesis, development and emergence of teeth

(Shimano. 1995).

Dental age can be assessed for deciduous or permanent teeth by determination of the

chronology of emergence of teeth through the oral tissues (eruption time) (Nizam et

a/. 2004: Pamer eta/., 2001), by counting the number of emerged teeth into the oral

cavity (Foti et al .• 2003), by tracing the calcification progress of dental tissues using

successive radiographic films (Demirjian eta/., 1973; Moorrees et al .. 1963; Nolla,

1960; Gam et al.. 1956). Dental age can also be assessed histologicaly by assessing

the teeth developmental stage of dried mandible and maxilla bones that have been

taken from dead children who their chronological ages are known at the time of

death (Logan and Kronfeld, 1933).

-The dental system is an integral part of the human body. Knowledge about dental age

can be applied in estimation of chronological age at the time of death (Frucht et al .•

2000), assisting the paediatric dentists and orthodontists to plan for a proper

treatment (Moorrees et a/., 1963), and can be used to assess the level of dental

development in certain medical conditions (Ribeiro et a/., 2002; Kjellberg et a/.,

2000).

Age estimation at death is one of the identification methods used by the forensic

anthropologists and odontologists to narrow down the potential identities of the

deceased individuals (Byers, 2001 ). Age estimation of sub-adult individuals is based

on a physiological assessment of dental and/ or skeletal age (Lewis and Flavel.

2006). Sub-adult stage can be defined as the period in which the skeletal and dental

tissues are in growing status (Byers, 2001 ).

Dental age seems to be better than skeletal age for age estimation at death as dental

age is less affected by variation in nutritional and endocrine status when compared to

other physiological age methods (Garnet a/., 1965 a, and b), and is correlated better

with the chronological age than skeletal age (Demirjian eta/., 1985).

It is important for every dentist treating children to have a good understanding of

development of the dentition. In interceptive orthodontic, knowing the time of each

stage of tooth development can give a general idea to dental clinicians in proposing

proper treatment plans and times. By way of example, prediction the emergence time

of permanent teeth based on root developmental stage can help in planning for serial

extraction (Moorrees et a/., 1963). Moreover, the time of apical part closure can help

in.anticipation the proper time for apexification.

Beside this, dental age can be used as a measurement tool to assess the degree of

effect of some diseases (e.g. Turner's syndrome or cleft lip and palate) (Ribeiro et

al., 2002; Hass eta/., 2001), or drugs (e.g. chemotherapy or Cortisone) (Lehtinen et

al., 2000; Nasman et al., 1997) on the dental development, this in tum will give a

2

general knowledge to dental clinicians about planning a proper dental treatment for

such cases.

1.2 Justification of the study

Variations in dental development exist between different populations (Reid and

Dean, 2006; Frucht et al., 2000; Davis and Hagg, 1994). Thus, foreign dental

developmental standards and data might not be accurate for the local people, and

each population should establish their own reference charts and standards. Therefore.

a valid standard of dental age in Malay population should be constructed. Dental age

based on time of permanent teeth eruption on Malay population has been conducted

on more than 2000 school children aged 5- 17 years (Nizam et al., 2003). Dental age,

however, based on radiographic standard of permanent teeth need to be investigated

since there is just one study available in this area (Mani et al., 2008).

3

1.3 General objective

To determine the radiographic dental age standard for Kelantanese Malay boys and

girls aged 5 to 16 years old.

1.4 Specific objectives

I) To evaluate the accuracy of Demirjians' methods (1973, 1976) in estimating the

chronological age of Kelantanese Malay male and female aged 5 to 16 years old.

2) To establish a new dental age standards for the Kelantanese Malay population by

modifying the Demirjian's method (1973); if Demirjian methods were not accurate

on the Kelantanese Malay population.

3) To compare the dental age standards of Kelantanese Malay with that of French­

Canadian children.

4) To determine the sexual dimorphism in the dental age assessment of all patients.

5) To assess the side differences of the dental age between the lower right and left

quadrants within the same patient.

6) To determine the median age of attainment of each developmental stage according

to Demirjian stages for the lower permanent left seven teeth for both sexes.

1.5 Hypothesis

11 The dental age which is estimated by Demirjians' methods (1973, 1976) are not in

accordance to the chronological age ofKelantanese Malay children.

2) Kelantanese Malay Children are advanced in dental age as compared to French­

Canadians.

3) Girls dental age is more advanced than boys' dental age.

4) Maturity scores and dental ages are equal in both sides of the lower jaw.

4

2.1 Tooth formation

Chapter 2

Literature Review

Many descriptions of the process of tooth formation have been written over the past

several decades. Teeth development from two types of cells: oral epithelium cells

form the enamel organ and mesenchymal cells form the dental papilla. Enamel

develops from the enamel organ, and dentin forms from the dental papilla. The

interaction of these epithelial and mesenchymal cells is vital to the initiation and

formation of the teeth. In addition to these cells, the neural crest cells contribute to

tooth development. The neural crest cells arise from the neural cells at an early stage

of development and migrate into the jaws, intermingling with mesenchymal cells.

They function by integrating with the dental papillae and epithelial cells of the early

enamel organ, which aids in the development of the teeth. The cells also function in

the development of the salivary glands, bone, cartilage, nerves, and muscles of the

face (Chandra eta/. 2004; Avery and Chiego, 2006).

The first sign of tooth formation is the development·vf dental lamina rising from the

oral epithelium. Dental lamina develops into a sheet of epithelial cells that pushes

into the underlying mesenchyme around the perimeter of both the maxillary and

mandibular jaws. At the leading edge of the lamina, 20 areas of enlargement appear

which form tooth buds for the 20 primary teeth. At this early stage, the tooth buds

have already determined tooth morphological class either an incisor or molar. This is

the result of gene expression (A very and Chiego, 2006). After primary teeth develop

from the buds, the leading edge of the lamina continues to grow to develop the

5

permanent teeth, which succeed the 20 primary teeth. This part of lamina is thus

called successional lamina. The lamina continuous posteriorly into the elongating

jaw and from it come the posterior teeth, which form behind the primary teeth. In this

manner, 20 of the permanent teeth replace the 20 primary teeth, and 12 posterior

permanent molars develop behind the primary dentition. The last teeth to develop are

the third molars, which develop about 15 years after birth (Avery and Chiego, 2006).

Because the molars do not succeed the primary teeth, they do not form from the

successional lamina but from the general lamina. The initiating dental lamina that

forms both the successional and general lamina begins to function in the sixth

prenatal week and continuous to function until the fifteenth year, producing all 52

teeth (Avery and Chiego, 2006; Nanci and Ten Cate, 2003).

Although tooth formation is a continuous process, it is characterized by a series of

easily distinguishable stages known as the bud, cap, and the bell stages (Figure 2.1 ).

Each stage is defined according to the shape of the epithelial enamel organ, which is

a part ofthe developing tooth (Avery and Chiego, 2006).

At this stage, the inner enamel epithelial cells are characterized by the shape of the

tooth they form. The cells of the enamel organ have differentiated into the outer

~namel epithelial cells which cover the enamel organ, and inner enamel epithelial

cells, which become the ameloblasts that form the enamel of the tooth crown.

6

DENT At. initiation ~ LAMINA

~~BUD m

Figure 2.1: Stages of tooth formation (Bud, Cap, and Bell stages) (Theslef, 2004)

During the bell stage, cells in the periphery of the dental papilla become odontoblasts

which form the dentin (Nanci and Ten Cate, 2003). These cells differentiate from

mesenchymal cells. When several increments of dentin have formed, the

differentiated ameloblasts deposit an enamel matrix. Dentinogenesis always precedes

amelogensis (A very and Chi ego, 2006; Chandra et a/. 2004: Nanci and Ten C ate.

2003).

2.1.1 Dentinogenesis

Increments of dentin are formed along the dentinoenamel junction. The dentinal

matrix is first a meshwork of collagen fibers, but within 24 hours it becomes

calcified. It is called predentin before ce'!dfication and dentin after calcification. As

each daily increment of predentin forms along the pulpal boundary, the adjacent

peripheral increment of predentin formed the previous day calcifies and becomes

dentin (Avery and Chiego, 2006; Nanci and Ten Cate, 2003).

2.1_.2 Amelogenesis

Ameloblasts begin enamel deposition after a few micrometers of dentin have been

deposited at the dentoenamel junction. At the bell stage, cells of the inner enamel

7

epithelium differentiate. They elongate and are ready to become active secretory

ameloblasts.

Only a few ameloblasts at the tip of the crown cusp begin to function initially. As the

process proceeds, more ameloblasts become active. and the increments of enamel

matrix become more prominent (A very and Chiego, 2006).

Growth of individual cusps by incremental deposition continues until tooth eruption.

This occurs in posterior multicuspid teeth as the ameloblasts continue to ditlerentiate

from the inner enamel epithelium and from enamel. Cusps then coalesce in the

intercuspal region of the crown (Nanci and Ten Cate. 2003).

2.1.3 Crown formation

As the process of amelogensis continues, the enamel matrix begins to mineralize. As

soon as the small crystals of mineral are deposited, they begin to grow in length and

diameter. The pattern of mineralization closely follows the pattern matrix deposition.

The first matrix deposited is the first enamel mineralized, occurring along the

dentinoenamel junction. Matrix formation and mineralization continue peripherally

to the tips of the cusps then laterally on the sides of the crown, following the enamel

incremental deposition pattern. Finally, the cervical region ofthe crown mineralizes

(Nanci and Ten Cate, 2003). Human enamel is known to form at a rate of

approximately 4 - urn per day. Ground section of enamel reveal what appear to be

periodic bands or cross striation at 4-um intervals across (Nanci and Ten Cate, 2003).

8

With the mineralization of enamel complete and its thickness established, the crown

ofthe tooth is formed (Avery and Chiego. 2006).

2.1.4 Development of the tooth root

As the crown develops, cell proliferation continues at the cervical region or base of

the enamel organ, where the inner and outer enamel epithelial cells join to form a

root sheath. When the crown is completed, the cells in the region of the enamel organ

continue to grow forming a double layer of cells termed the epithelial root sheath or

Hertwig's root sheath. The inner cell layer of the root sheath forms from the inner

enamel epithelium or ameloblasts in the crown, and enamel is produced. In the root,

these cells induce odontoblasts of the dental papilla to differentiate and form dentin.

The root sheath originates at the point that the enamel deposits end (~anci and Ten

Cate, 2003).

As the odontoblasts differentiate along the pulpal boundary, root Dentinogenesis

proceeds and the root lengthens. Dentin formation continues from the crown into the

root. The dentin tapers from the crown into the root to the apical epithelial

diaphragm. Dentinogenesis continues until the appropriate root length is developed.

The root then thickens until the apical opening is restricted to approximately 1 to 3

mm, which is insufficient to allow neural and vascular communication between the

pulp and the peridontium (A very and Chi ego, 2006).

With the increase in root length, the root begins eruptive movements, which provides

space for further lengthening of the root. The root lengthens at the same rate as the

tooth eruptive movements occur (Avery and Chiego, 2006).

9

2.2 Age estimation at death for sub-adults

Methods of estimating age at the time of death are many and vary. It is a parameter

that once known, can be extremely useful in identifying an individual and it can

narrow down the potential identification identity (Byers. 200 I).

There are various definitions for adult and sub-adult stage in relation to age

estimation at death that has been used by many researchers. McDonough and

Stedman ( 1994) defined adult stage as when the person is fully grown and physically

mature. Byers {200 l) defined sub-adult stage as the period in which the skeletal and

dental tissues are in growing status; as permanent teeth growing to reach the apical

closure in the dental tissues and the secondary ossification centres of the bones

continue to growth until they union their associated primary centres. \\'hen the

growth ceases, the estimation of age will be based on deteriorating tissues as several

structures in the body undergo changes over time; for example, the attrition of teeth

or apposition of layers of cementum after the tooth is completely formed and (Lewis

and Flavel, 2006; Byers, 2001). Byers (2001) definition is being used in this

literature review to describe the sub-adult stage .

.. Age estimation of deceased sub-adult individuals is based on a physiological

~ssessment of dental or skeletal maturation as they continue to develop until late into

the second decade of life or the beginning of the third one (Byers, 2001 ). Thus,

accurate age estimation for sub-adult relies on the accurate conversion of these two

biological ages (dental and skeletal) into chronological age (Lewis and Flavel, 2006).

10

2.2.1 Skeletal tissues methods for sub-adults

The growth of the human skeleton is a complex process that is not fully understood.

and the available information indicates that bones form within cartilaginous

li\' ~; precursors by the deposition of calcium salts (Byers. 200 I).

The deposition of calcium occurs initially in multiple areas, called primary and

secondary areas of ossification (Byers, 2001). Primary centres of ossification or

primary point of ossification can be defined as the first site where bone begins to

form in the shaft of a long bone, or in the body of an irregular bone, while secondar)·

centres of ossification are the centres of bone formation appearing later than the first

centres and usually in epiphysis (McDonough and Stedman. 1994). Both centres

eventually grow together forming larger segments such as diaphysis and epiphysis

(Figure 2.2). When these areas of ossification unite, bone growth proceeds in earnest.

Long bones grow to their ends under the epiphysial caps. At a mostly genetically

predetermined time, the epiphyses fuse to the diaphyses (at the metaphyses), causing

growth to cease (Bayer, 2001).

Other bones grow by apposition over all surfaces i.e. growth accomplished by the

addition of new layers on those previously formed one (e.g. those of the wrist and

ankles), while the skull grows along the edges of its bones at the suture lines (Byers,

2001).

11

.'I ;~ tl :~ ~ ~' ' ~:~.-___ __.

\,

Ihaphyse

Figure 2.2: Schematic drawing ofEpiphyse, Metaphyse, and Diaphyse (Adapted from Feneis & Dauber, 2000. p. 47)

2.2.1.1 UI!_ion of primary ossification centres

The time of appearance of primary and secondary centres of ossification is

potentially valuable in age estimation (Stewart, 1979). Bone is deposited in these

centres according to a rough schedule, so the amount of their development in a

skeleton indicates an approximate age at death (Byers, 2001). Additionally, the union

of secondary centres to their associated primary centres also follows a rough

schedule that can be utilized in a similar manner, unfortunately the small size and

fragility of these bony structures make their recovery difficult, and thus they have

12

little utility in age estimation (Byers, 2001 ). However, the union of primary centres

to each others can be used occasionally because these structures are more likely to be

recovered (Stewart, 1979).

The main primary centres that can be used for age estimation are the skull. mandible.

atlas, and axis. In the skull, two types of unions occur. First, new born babies exhibit

gaps where three or more bones come together, called fontanels such as frontal,

sphenoid, mastoid. and occipital fontanels. In addition to these gaps. the ossification

centres of a number of cranial bones unite during growth as the right and left halves

of the frontal bone and left and right halves of the mandible (Stewart, 1979).

According to Terry ( 1942). the timing of the more reliable primary centres for age

estimation was as follows: (Adaptt!d from Stewart. 1979: p. I 39)

Bone Location Period of closure/union

Sphenoid and mastoid Close soon after birth Fontanels Occipital Closes during first year

Frontal Closes during second year

Mandible Symphysis Union completed in second year

Said to remain open in 8 to 9

Fi"..>ntal bone Metopic suture percent of whites. When closure takes place, it begins in second year

Atlas Posteriorly Union occurs in third year

Anteriorly Union occurs about the sixth year

Axis Dens, body and two sides Union of all four parts occurs of arch during third year

Squamous with lateral Union completed in fifth year

Occipital bone parts

Lateral parts with basilar Union completed before seventh parts year

13

...

Development of the centres of ossification of the hand and foot are useful in

assessment of biological age of a child (Malina et a/ .. 200•t). One of the method

which uses to assess the hand wrist is the Greulich and Pyle radiographic atlas of

skeletal de\elopment (Malina et a/ .. 2004 ).

2.2.1.2 Epiphysial union

Bones grow by the deposition of osseous material on their ends. This process starts

after the primary centres of ossification have fused with each other and the entire

cartilaginous precursor has transformed into bone. At this point, their ends do not

exhibit bony joint surfaces; instead they are covered by cartilaginous joint area. Later

on, the epiphysial caps unite to their diaphyses leaving a temporarily visible line.

Finally, this line becomes completely obliterated by the mechanisms of bone

remodelling (Byers, 200 I).

There are numerous epiphysial centres in the human skeleton. All long bones have at

least two (one on each end) or more (e.g. the femur has four). Similarly, the first ten

ribs have two, one on the head and the other on the auricular surface of the tubercle.

By contrast, each metacarpal and metatarsal bone exhibits only one, which is located

on their proximal ends. The bottom twenty two vertebrae have at least five epiphysial

centres (Byers, 2001 ).

14

One of the schedules which are used to assess the epiphysial union was introduced

by Buikstra and Ubelaker (1994) (Figure 2.3). the authors determined the range of

age within which the epiphysial fusion occurs for several bones based on samples of

NatiYe American children. Generally. the bones from the early part of this range of

age are recognisable by the presence of clearly visible lines that appear to cut deeply

into the bones (same as in Figure 2.4b), whereas those that have less visible and/or

almost obliterated lines are more often from the end of these ranges (same as in

Figure 2.4c) (Byers, 200 I). It seems that schedules which was made by Buikstra and

Ubelker ( 1994) are accurate for estimating the age between 10 to 25 years of age.

because very few epiphysial centres fuse before I 0 years and the majority of

epiphysial centres fused by the age of 25 years (Byers. :!00 I ).

15

Vtol itii.JI":i!: ta-na

Occipita' (a}

I • I I

0 2 4 6 8

------+-M I ~~;'":r r n n.:c!:>l:<d sv:r::hcnc!rc.sl;; , . M

C:<::·ncl::· <ecial ep•.

Sacrum: S 1 -S~ __ ...._ ____ M

Sac~urn: S2-S3 --..i----M Sacrum: SJ-SS ------M

Rudiut;: di~;: -M

Femur.IJI'•'ialt!r hod 1

' M : Tibia: pt'OX.l I M

Femur: headtl.~S<!r troc"'l I M :numrm;r.: rll't:H.l ____ _.._,.

S~;pu'a: acrcmion.'os ccxae: tliac c;a;:;l ____ .....__., j-:amu _ dir.UHlub:JirC)( .

Fitx.la: ds~ /tb,a: c.hd.M

-'-----"'

--==--~"" Fll - '· umerus: ::l1sta1 ept

i i I I

I I I . 10 t2 14 16 18 20 22 24 26 28 30 32

A(lehyeam

Figure 2.3: Buikstra and Ubelker's Schedule of epiphysial union (Adapted from Byers (2001), p.212).

16

Figure 2.4: Stages of epiphysial union of the distal femur: a) no union (missing epiphysis); b) unfused; c) fused; d) obliterated (adapted from Byers (2001)\>

p.211).

2.2.1.3 Long bones lengths

From the time of first appearance of the long bones up to birth. the relationship

between age and long bone length appears linear; however, the method of age

estimation for non-adult based on the measured length of specific long bones is one

that has been used cautiously, it is a method that suffers from inaccuracy due to the

wide variation seen in absolute growth in any sample population and quite wide

interracial variation and as such, population specific tables should be used if

available when utilizing this method (Byers, 2001). In addition, the method gives

estimation interval which is broad for forensic purposes, being incremented in six-

months to one year interval (Weaver, 1986).

2.2.2 Dental tissues methods for sub-adult

Unlike the union of ossification centres, most, if not all, of developing teeth are

likely to remain in place during the process of skeletonization (Stewart, 1979). When

compared with skeletal development, dental development also showed to be less

17

affected by the diseases and nutrition (Weaver, 1986; Gamet a/., 1965a). Moreover,

dental development showed to be a more reliable means of estimating the age of sub­

adult (Stewart, 1963 and 1954).

2.2.2.1 Eruption time and teeth counts

"Eruption" or "clinical emergence" refers to the passage of a tooth through the

alveolar process and perforation of the gums. It is the first choice for fast and simple

visual evidence of age, Gron ( 1962) considered a tooth erupted if it had just pierced

the gingiva. but was no more than 3mm from the gingival level. The first use of

eruption as an indicator of development was in England in 1837 when the factory act

stipulated that: a child without a second permanent molar would not be allowed to

work in the factories. In the first quarter of the 201h century. dental criteria were used

as an indicator for school entrance purposes (Demirjian. 1978).

The chronology of emergence for both deciduous and permanent teeth has been

broadly studied as a method of age estimation, such studies differ with regard to

selection of patients such as number of patients, and cross sectional or loilgitudinal

study (Saleem and Hagg eta/., 1996; Pahkala et a/., 1991; Manji and Mwaniki, 1985;

Hoffding eta/., 1984; Lee eta/., 1965). Nizam eta/. (2003) conducted a cross­

sectional study of eruption time of permanent teeth in Kelantan state, Malaysia. More

than 2300 school children aged 5 to 17 years old were evaluated. Those children

included into the study were children of Malay origin and had no history of

extraction of deciduous teeth due to caries. Those with congenital anomalies, with

history of any systemic disease and those undergoing orthodontic treatment were

excluded from the study.

18

Counting of the emerged deciduous and permanent teeth was considered one of the

dental age methods which showed good estimation of age. Foti et a/. (2003)

conducted a study in the aim of providing mathematical models for age calculation

based on counting of emerged teeth. and. if possible. tooth germs. Eight hundred and

ten panoramic radiographs of 397 boys and 413 girls of French origin from 6.10 to

21.08 years of age (average age of 12.63 years) were assessed. They defined the

criterion of tooth eruption. from a radiological point of view; the line lying over the

erupting tooth"s cusps had to reach over the line joining the mesial and the distal

cemento-enamel junctions of adjacent teeth. The number of germs was also noted. A

germ was considered to be present at the stage of crown calcification, corresponding

to Demirjian·s stage (A) that is the start of calcification of the cusp tips. The authors

came out with three regressive models that did not yield significant difference

between the means of estimated age and real age, and they concluded that these

models really provide reliable age estimations.

Hagg and Taranger ( 1985) conducted a study to establish and test the validity of a

dental age based on counting the emerged deciduous and 29 permanent teeth. They

examined more than 200 Swedish children longitudinally at intervals of 1, 3, 6, 12,

18 months then annually from 2 years to 18 years. The emergence of teeth was

assessed clinically. The authors came out with values representing the number of

teeth and the chronological age, and then these values were examined cross­

sectionally on another 200 samples of Swedish children to test the validity. The

results showed difference between the real age and estimated age to be around one

month.

19

2.2.2.3 Radiographic methods

Age estimation for sub-adult can also be assessed by tracing the tooth calcification

by radiographs; since it represents a series of recognizable events that occur in the

same sequence from an initial event (beginning of calcification of the crown) to a

constant end point (closure of the apex) (Moorrees eta/., 1963). It seems that the

study of dental age based on criteria of calcification of the teeth seen in radiographic

is superior to the teeth emergence time; as the emergence of teeth is a short period

event. thus it is difficult to detect it exactly. while calcification of teeth is a

continuous event; which starts form calcification of the crown to fully form of apical

part and it can be traced by permanent records such as the radiograph films

(Moorrees et a/.. 1963 ). In addition. the emergence can be affected by a diverse

range of factors as the local oral factors such as infection of the deciduous

predecessor (Yawaka et a/., 2002; Brook and Winter, 1975), or influence of

crowding that could delay the tooth emergence, pathology, trauma, and the presence

of supernumerary teeth (Suri eta/., 2004). Also, emergence time can be affected by

severe protein-calorie malnutrition (Demirjian, l Q78). Moreover, the technique is

limited to those periods when teeth are erupting (i.e. 0-3 years for the deciduous and

5-14 years for the permanent dentition), and the various techniques rely on different

definitions of the term eruption.

The types of radiograph films which are usually used for dental age included:

intraoral radiographs (periapical film) (Demirjian and Goldstein, 1976) or extraoral

radiographs such as panoramic (Demirjian eta/., 1973) or lateral oblique radiographs

(Moorrees et al., 1963; Nolla, 1960). There is no difference between these types of

20

films as long as the tooth stage can be assessed clearly. However, periapical films

seems to be easily obtained for children below five years old (Demirjian and

Goldstein. 1976).

Gleiser and Hunt, in 1955. studied 25 boys and 25 girls longitudinally, from birth to

age I 0, and traced the development of the first permanent mandibular molar only by

using lateral oblique radiograph. They described 15 different stages of maturity, from

the calcification of the cusp tip to closure of the apex. The description of the stages is

based on length criteria, as Y2 of the crown or % of the root completed (Demirjian,

1978).

~olla (1960) described a method based on 10 length stages oftooth development in

order to develop norms for American children that displayed the average

development of teeth for males and females aged between 5 to 18 years, and to

develop tables that could be used to estimate chronological age based on the degree

of observed dental development. These developmental stages were studied

longitudinally for both the maxillary and mandibular teeth in 25 boys and 25 girls

giving the total number of lateral oblique radiographs of 1746 for the female sample,

and 1656 for the male sample. She assessed the teeth from the right and left sides. A

score of 1-10 was assigned to each stage, starting from the presence of the crypt

without calcification, to the completion of the apical end. Nolla also suggested that if

a tooth was located between two stages, the solution was to use the lower stage and

to add 0.5 to the value assigned to that specific tooth. The description of the stages is

based on length criteria. She found the sexual difference in the rate of dental

development was not significant; the development, however, begins earlier in girls.

21

Similarly, few developmental differences were shown between right and left teeth of

same kind.

In 1961. Fanning applied Gleiser and Hunt's 13 calcification stages of dental

development to all mandibular and maxillary incisors. A total number of seven more

stages were added for more precision (two initial stages, two for cleft formation in

the molars, and three to describe the different degrees of apex closure). The

description of the stages is based on length criteria (Demirjian, 1978). However these

added stages proved to be too difficult to differentiate between successive stages

(Demirjian. 1978) .

Moorrees et a/. (1963) studied the development pattern of eight mandibular and two

maxillary incisors permanent teeth of 380 children from birth until 25 years of age.

The sample radiographs were collected from Boston (Forsyth Dental Infirmary) and

Ohio (Fels Research Institute, Yellow Springs). The aim was to obtain norms for the

age of attainment for each of the eight mandibular and maxillary incisor teeth. The

authors utilized I 3 calcification stages of dental development of single rooted teeth

and 14 stages for multi rooted teeth and the stages is based on length criteria (Yz of

the crown or % of the root completed). The incisors were assessed from intraoral

radiographs (Boston children); while uniradicular and multiradicular posterior teeth

were assessed from lateral or oblique jaw radiographs (Ohio children). The authors

derived a mean age of attainment for each stage of each tooth and graphically

represented the results including ± 2 standard deviation age limits.

22

Moorrees' method has been applied on Sardinian population where Diaz eta/. (1993)

assessed cross-sectionally 382 healthy children (178 boys and 204 girls). A single

OPG was examined for each patient. The authors evaluated the development of

permanent mandibular canines. premolars. and molars only. The author used OPGs

instead of lateral oblique which was used by Moorrees' method because as long as

the stage of the tooth can be read so the any radiographic image can be used. The

results showed differences in dental development between the North American

children and Sardinian which accounting for a delayed dental maturation in Sardinian

children.

2.2.2.3.1 Demirjian's Method (1973)

Demi~jian. Goldstein and Tanner in 1973 have developed a method of estimating

dental age based upon the stages of dental development seen in radiographs, where

the authors found that radiographic dental age methods were more reliable indicator

of dental age than tooth emergence; as tooth emergence can be affected by local oral

factors such as infection, pathology, and trauma. Also, emergence time can be

affected by severe protein-calorie malnutrition (Demirjian et al., 1973).

Demirjian et al. used panoramic radiographs as the image of the mandibular region in

t~e OPG was clear and only little distortion which is around 3 to 10% (Sapoka and

Demirjian, 1971). Demirjian considered this as not a drawback because the rating

system is based on shape criteria and relative values of the developing teeth rather

than on absolute lengths (Demirjian, 1978).

23

The sample used by Demirjian in 1973 study, consisted of 1446 males and 1482

females of French-Canadian origin aged between 2 and 20 years. The authors divided

the developmental stages of the tooth into 8 stages from A to H ( 4 for crown

development and 4 for root development) starting from the beginning of calcification

through to final mature form (with 0 indicating calcification not yet commenced)

(Figure 2.5). The authors assigned developmental stages based on shapes of teeth

which are easily recognisable and not on absolute length (Demirjian eta/., 1973).

Demirjian et al. ( 1973) have created their method based on the method described by

Tanner et a/. ( 1962) in relation to skeletal age, where each bone was given a score

depending on its stage. The scores of all bones then added together to give a total

maturity score which can be converted directly into a skeletal age using an

appropriate table of standards. Thus, for dental age, each tooth is given a score

depending on its stage. The scores of all the teeth are then added together to give a

total 'maturity score' (MS) which can be converted directly into 'dental age' (DA)

using an appropriate table of standards.

The final scores for each tooth, previously constrained each to be 100, are allowed to

vary so that only their sum (or average) over all the teeth is 100. This makes

allowance for the different ages at which different teeth reach maturity. Boys and

girls are given different systems of scores. The stages of the tooth development are

shown respectively below in Figure 2.5

24